This invention relates generally to a computer system for use between a data terminating user and a multitude of data terminating hosts. More particularly, the present invention relates to a system for enabling a first data terminating host to inform a digital communications network of a desired transfer to a second host whereby the network conveys requests to a node which initiates a concurrent virtual connection to the second host.
It has been known for some time that a user may connect his computer terminal via a modem to a host computer at a remote location from the user. The modem facilitates a call over telephone lines to the host computer. The user terminal and the host computer can be in communication, or "on-line", by the phone call connection. A connection to a host computer may be desirable for several reasons. For example, the host computer may have substantially enhanced computing capability compared to that of the user terminal. The user terminal may be a small computer in itself capable of performing some computations. Or, the user terminal may be a "dumb terminal" which relies solely on a host for all of its computing. Besides offering enhanced computing capability, the host may have data storage capacity needed by the user. The host may also offer special services otherwise not available to the user, such as, up-to-the-minute weather forecasts, news service, or stock market reports.
Digital communications networks have been used to access remote hosts with local telephone access. Communications processors, called nodes, are located for user convenience. When users call modems on these local nodes, they are asked what remote host they need to be connected to. The network facilitates the virtual connection to a node adjacent to the desired host and then to the remote host itself.
Today, some companies such as CompuServe.RTM. Incorporated offer their subscribers a multihost system. Several host computers are available to perform various tasks for terminal users. Prior to the subject invention, a user would have to make a call through his modem or communications network to access each host. Besides the inconvenience of requiring the users to learn the phone numbers or host addresses for each host, and what hosts provide what services, this process was also inefficient because it required the user to manually initiate a new connection to access a different host.
By using the present invention, any host within a network may redirect a user to another host as deemed necessary without requiring user involvement to initiate a second call. In other words, the user will gain from the efficiency of making one connection to the host and having the multihost system determine the appropriate host computer for the user to be in communication with at any given time. The multihost system, while in communication with the user, will respond by transferring computing responsibility from one host to another as the user's profile and requests indicate. The user will not necessarily know that his call has been deflected to another host. One initiated connection is all that is needed to let the multihost system decide which host is most suited to handling the user's needs. To summarize, the present invention provides a means of transferring a connection made between a data terminating user and a-first data terminating host to a second data terminating host. The first and second virtual connections are routed over the optimal path in a distributed digital communications network. The first host informs the network of the desired transfer and the desired second host' s address. The first host conveys the request to a node in the network in communication with the user (the "PAD"). The PAD initiates a concurrent virtual connection to a second host. When the PAD is informed that the second connection is successful, the PAD conveys success to the first host.
At the same time, the PAD also sends the second host operating parameters of the user. The first host may then send arbitrary amounts of information to the PAD to be forwarded to the second host. At the conclusion of this "announcement", the first host sends a disconnect to the PAD which responds by completing the transfer of the virtual circuit. The PAD is referred to as a TR node or a gateway node depending upon whether the user is a regular subscriber to the host's network or external to the network. When the user is an "on-line" regular customer of the multihost network, the user's modem accesses the network's TR node. Furthermore, the present invention allows external networks to access call deflection. When an external network accesses the multihost network of the present invention, the external network will pass through a gateway node.
The present invention offers several advantages over previously known systems of user-to-host communication. Using the present invention, a user terminal, making one call through a modem, can access numerous hosts having different addresses. Previously, it has been common for the user terminal to hang up on the first host and dial a new phone number to reach a second host. Or, in other previous systems where one host is in network with a second host, the user could access the second host without hanging up on the first host but the first host had to remain part of the connection. If the first host were to drop out, the connection to the second host would terminate. In other words, the first host acts as a switchboard in this known arrangement. Networks that route connections by relaying them through intermediate hosts waste both valuable host and node computer resources. Freeing the first host to process more data for customers, for example, allows the first host more availability for its intended function. Although the present invention incorporates the first host, it allows the first host to be disconnected after connection is made to a second host, without requiring the user to make a second phone call. Further objects and advantages of the present invention will become more apparent when viewed in light of the accompanying drawings and the following detailed description.